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48 #include "types/simple.h"
49 #include "types/nbnxn_pairlist.h"
50 #include "types/nb_verlet.h"
51 #include "types/ishift.h"
52 #include "types/force_flags.h"
53 #include "../nbnxn_consts.h"
56 #include "thread_mpi/atomic.h"
59 #include "nbnxn_cuda_types.h"
60 #include "../../gmxlib/cuda_tools/cudautils.cuh"
61 #include "nbnxn_cuda.h"
62 #include "nbnxn_cuda_data_mgmt.h"
64 #if defined TEXOBJ_SUPPORTED && __CUDA_ARCH__ >= 300
68 /*! Texture reference for nonbonded parameters; bound to cu_nbparam_t.nbfp*/
69 texture<float, 1, cudaReadModeElementType> nbfp_texref;
71 /*! Texture reference for Ewald coulomb force table; bound to cu_nbparam_t.coulomb_tab */
72 texture<float, 1, cudaReadModeElementType> coulomb_tab_texref;
74 /* Convenience defines */
75 #define NCL_PER_SUPERCL (NBNXN_GPU_NCLUSTER_PER_SUPERCLUSTER)
76 #define CL_SIZE (NBNXN_GPU_CLUSTER_SIZE)
78 /***** The kernels come here *****/
79 #include "nbnxn_cuda_kernel_utils.cuh"
81 /* Top-level kernel generation: will generate through multiple inclusion the
82 * following flavors for all kernels:
83 * - force-only output;
84 * - force and energy output;
85 * - force-only with pair list pruning;
86 * - force and energy output with pair list pruning.
89 #include "nbnxn_cuda_kernels.cuh"
90 /** Force & energy **/
92 #include "nbnxn_cuda_kernels.cuh"
95 /*** Pair-list pruning kernels ***/
98 #include "nbnxn_cuda_kernels.cuh"
99 /** Force & energy **/
100 #define CALC_ENERGIES
101 #include "nbnxn_cuda_kernels.cuh"
105 /*! Nonbonded kernel function pointer type */
106 typedef void (*nbnxn_cu_kfunc_ptr_t)(const cu_atomdata_t,
111 /*********************************/
113 /* XXX always/never run the energy/pruning kernels -- only for benchmarking purposes */
114 static bool always_ener = (getenv("GMX_GPU_ALWAYS_ENER") != NULL);
115 static bool never_ener = (getenv("GMX_GPU_NEVER_ENER") != NULL);
116 static bool always_prune = (getenv("GMX_GPU_ALWAYS_PRUNE") != NULL);
119 /* Bit-pattern used for polling-based GPU synchronization. It is used as a float
120 * and corresponds to having the exponent set to the maximum (127 -- single
121 * precision) and the mantissa to 0.
123 static unsigned int poll_wait_pattern = (0x7FU << 23);
125 /*! Returns the number of blocks to be used for the nonbonded GPU kernel. */
126 static inline int calc_nb_kernel_nblock(int nwork_units, cuda_dev_info_t *dinfo)
132 max_grid_x_size = dinfo->prop.maxGridSize[0];
134 /* do we exceed the grid x dimension limit? */
135 if (nwork_units > max_grid_x_size)
137 gmx_fatal(FARGS, "Watch out, the input system is too large to simulate!\n"
138 "The number of nonbonded work units (=number of super-clusters) exceeds the"
139 "maximum grid size in x dimension (%d > %d)!", nwork_units, max_grid_x_size);
146 /* Constant arrays listing all kernel function pointers and enabling selection
147 of a kernel in an elegant manner. */
149 static const int nEnergyKernelTypes = 2; /* 0 - no energy, 1 - energy */
150 static const int nPruneKernelTypes = 2; /* 0 - no prune, 1 - prune */
152 /*! Pointers to the default kernels organized in a 3 dim array by:
153 * electrostatics type, energy calculation on/off, and pruning on/off.
155 * Note that the order of electrostatics (1st dimension) has to match the
156 * order of corresponding enumerated types defined in nbnxn_cuda_types.h.
158 static const nbnxn_cu_kfunc_ptr_t
159 nb_default_kfunc_ptr[eelCuNR][nEnergyKernelTypes][nPruneKernelTypes] =
161 { { k_nbnxn_cutoff, k_nbnxn_cutoff_prune },
162 { k_nbnxn_cutoff_ener, k_nbnxn_cutoff_ener_prune } },
163 { { k_nbnxn_rf, k_nbnxn_rf_prune },
164 { k_nbnxn_rf_ener, k_nbnxn_rf_ener_prune } },
165 { { k_nbnxn_ewald_tab, k_nbnxn_ewald_tab_prune },
166 { k_nbnxn_ewald_tab_ener, k_nbnxn_ewald_tab_ener_prune } },
167 { { k_nbnxn_ewald_tab_twin, k_nbnxn_ewald_tab_twin_prune },
168 { k_nbnxn_ewald_tab_twin_ener, k_nbnxn_ewald_twin_ener_prune } },
169 { { k_nbnxn_ewald, k_nbnxn_ewald_prune },
170 { k_nbnxn_ewald_ener, k_nbnxn_ewald_ener_prune } },
171 { { k_nbnxn_ewald_twin, k_nbnxn_ewald_twin_prune },
172 { k_nbnxn_ewald_twin_ener, k_nbnxn_ewald_twin_ener_prune } },
175 /*! Pointers to the legacy kernels organized in a 3 dim array by:
176 * electrostatics type, energy calculation on/off, and pruning on/off.
178 * Note that the order of electrostatics (1st dimension) has to match the
179 * order of corresponding enumerated types defined in nbnxn_cuda_types.h.
181 static const nbnxn_cu_kfunc_ptr_t
182 nb_legacy_kfunc_ptr[eelCuNR][nEnergyKernelTypes][nPruneKernelTypes] =
184 { { k_nbnxn_cutoff_legacy, k_nbnxn_cutoff_prune_legacy },
185 { k_nbnxn_cutoff_ener_legacy, k_nbnxn_cutoff_ener_prune_legacy } },
186 { { k_nbnxn_rf_legacy, k_nbnxn_rf_prune_legacy },
187 { k_nbnxn_rf_ener_legacy, k_nbnxn_rf_ener_prune_legacy } },
188 { { k_nbnxn_ewald_tab_legacy, k_nbnxn_ewald_tab_prune_legacy },
189 { k_nbnxn_ewald_tab_ener_legacy, k_nbnxn_ewald_tab_ener_prune_legacy } },
190 { { k_nbnxn_ewald_tab_twin_legacy, k_nbnxn_ewald_tab_twin_prune_legacy },
191 { k_nbnxn_ewald_tab_twin_ener_legacy, k_nbnxn_ewald_tab_twin_ener_prune_legacy } },
194 /*! Return a pointer to the kernel version to be executed at the current step. */
195 static inline nbnxn_cu_kfunc_ptr_t select_nbnxn_kernel(int kver, int eeltype,
196 bool bDoEne, bool bDoPrune)
198 assert(kver < eNbnxnCuKNR);
199 assert(eeltype < eelCuNR);
201 if (NBNXN_KVER_LEGACY(kver))
203 /* no analytical Ewald with legacy kernels */
204 assert(eeltype <= eelCuEWALD_TAB_TWIN);
206 return nb_legacy_kfunc_ptr[eeltype][bDoEne][bDoPrune];
210 return nb_default_kfunc_ptr[eeltype][bDoEne][bDoPrune];
214 /*! Calculates the amount of shared memory required for kernel version in use. */
215 static inline int calc_shmem_required(int kver)
219 /* size of shmem (force-buffers/xq/atom type preloading) */
220 if (NBNXN_KVER_LEGACY(kver))
222 /* i-atom x+q in shared memory */
223 shmem = NCL_PER_SUPERCL * CL_SIZE * sizeof(float4);
224 /* force reduction buffers in shared memory */
225 shmem += CL_SIZE * CL_SIZE * 3 * sizeof(float);
229 /* NOTE: with the default kernel on sm3.0 we need shmem only for pre-loading */
230 /* i-atom x+q in shared memory */
231 shmem = NCL_PER_SUPERCL * CL_SIZE * sizeof(float4);
232 /* cj in shared memory, for both warps separately */
233 shmem += 2 * NBNXN_GPU_JGROUP_SIZE * sizeof(int);
235 /* i-atom types in shared memory */
236 shmem += NCL_PER_SUPERCL * CL_SIZE * sizeof(int);
238 #if __CUDA_ARCH__ < 300
239 /* force reduction buffers in shared memory */
240 shmem += CL_SIZE * CL_SIZE * 3 * sizeof(float);
247 /*! As we execute nonbonded workload in separate streams, before launching
248 the kernel we need to make sure that he following operations have completed:
249 - atomdata allocation and related H2D transfers (every nstlist step);
250 - pair list H2D transfer (every nstlist step);
251 - shift vector H2D transfer (every nstlist step);
252 - force (+shift force and energy) output clearing (every step).
254 These operations are issued in the local stream at the beginning of the step
255 and therefore always complete before the local kernel launch. The non-local
256 kernel is launched after the local on the same device/context, so this is
257 inherently scheduled after the operations in the local stream (including the
259 However, for the sake of having a future-proof implementation, we use the
260 misc_ops_done event to record the point in time when the above operations
261 are finished and synchronize with this event in the non-local stream.
263 void nbnxn_cuda_launch_kernel(nbnxn_cuda_ptr_t cu_nb,
264 const nbnxn_atomdata_t *nbatom,
269 int adat_begin, adat_len; /* local/nonlocal offset and length used for xq and f */
270 /* CUDA kernel launch-related stuff */
272 dim3 dim_block, dim_grid;
273 nbnxn_cu_kfunc_ptr_t nb_kernel = NULL; /* fn pointer to the nonbonded kernel */
275 cu_atomdata_t *adat = cu_nb->atdat;
276 cu_nbparam_t *nbp = cu_nb->nbparam;
277 cu_plist_t *plist = cu_nb->plist[iloc];
278 cu_timers_t *t = cu_nb->timers;
279 cudaStream_t stream = cu_nb->stream[iloc];
281 bool bCalcEner = flags & GMX_FORCE_VIRIAL;
282 bool bCalcFshift = flags & GMX_FORCE_VIRIAL;
283 bool bDoTime = cu_nb->bDoTime;
285 /* turn energy calculation always on/off (for debugging/testing only) */
286 bCalcEner = (bCalcEner || always_ener) && !never_ener;
288 /* Don't launch the non-local kernel if there is no work to do.
289 Doing the same for the local kernel is more complicated, since the
290 local part of the force array also depends on the non-local kernel.
291 So to avoid complicating the code and to reduce the risk of bugs,
292 we always call the local kernel, the local x+q copy and later (not in
293 this function) the stream wait, local f copyback and the f buffer
294 clearing. All these operations, except for the local interaction kernel,
295 are needed for the non-local interactions. The skip of the local kernel
296 call is taken care of later in this function. */
297 if (iloc == eintNonlocal && plist->nsci == 0)
302 /* calculate the atom data index range based on locality */
306 adat_len = adat->natoms_local;
310 adat_begin = adat->natoms_local;
311 adat_len = adat->natoms - adat->natoms_local;
314 /* When we get here all misc operations issues in the local stream are done,
315 so we record that in the local stream and wait for it in the nonlocal one. */
316 if (cu_nb->bUseTwoStreams)
318 if (iloc == eintLocal)
320 stat = cudaEventRecord(cu_nb->misc_ops_done, stream);
321 CU_RET_ERR(stat, "cudaEventRecord on misc_ops_done failed");
325 stat = cudaStreamWaitEvent(stream, cu_nb->misc_ops_done, 0);
326 CU_RET_ERR(stat, "cudaStreamWaitEvent on misc_ops_done failed");
330 /* beginning of timed HtoD section */
333 stat = cudaEventRecord(t->start_nb_h2d[iloc], stream);
334 CU_RET_ERR(stat, "cudaEventRecord failed");
338 cu_copy_H2D_async(adat->xq + adat_begin, nbatom->x + adat_begin * 4,
339 adat_len * sizeof(*adat->xq), stream);
343 stat = cudaEventRecord(t->stop_nb_h2d[iloc], stream);
344 CU_RET_ERR(stat, "cudaEventRecord failed");
347 if (plist->nsci == 0)
349 /* Don't launch an empty local kernel (not allowed with CUDA) */
353 /* beginning of timed nonbonded calculation section */
356 stat = cudaEventRecord(t->start_nb_k[iloc], stream);
357 CU_RET_ERR(stat, "cudaEventRecord failed");
360 /* get the pointer to the kernel flavor we need to use */
361 nb_kernel = select_nbnxn_kernel(cu_nb->kernel_ver, nbp->eeltype, bCalcEner,
362 plist->bDoPrune || always_prune);
364 /* kernel launch config */
365 nblock = calc_nb_kernel_nblock(plist->nsci, cu_nb->dev_info);
366 dim_block = dim3(CL_SIZE, CL_SIZE, 1);
367 dim_grid = dim3(nblock, 1, 1);
368 shmem = calc_shmem_required(cu_nb->kernel_ver);
372 fprintf(debug, "GPU launch configuration:\n\tThread block: %dx%dx%d\n\t"
373 "Grid: %dx%d\n\t#Super-clusters/clusters: %d/%d (%d)\n",
374 dim_block.x, dim_block.y, dim_block.z,
375 dim_grid.x, dim_grid.y, plist->nsci*NCL_PER_SUPERCL,
376 NCL_PER_SUPERCL, plist->na_c);
379 nb_kernel<<<dim_grid, dim_block, shmem, stream>>>(*adat, *nbp, *plist, bCalcFshift);
380 CU_LAUNCH_ERR("k_calc_nb");
384 stat = cudaEventRecord(t->stop_nb_k[iloc], stream);
385 CU_RET_ERR(stat, "cudaEventRecord failed");
389 void nbnxn_cuda_launch_cpyback(nbnxn_cuda_ptr_t cu_nb,
390 const nbnxn_atomdata_t *nbatom,
395 int adat_begin, adat_len, adat_end; /* local/nonlocal offset and length used for xq and f */
398 /* determine interaction locality from atom locality */
403 else if (NONLOCAL_A(aloc))
410 sprintf(stmp, "Invalid atom locality passed (%d); valid here is only "
411 "local (%d) or nonlocal (%d)", aloc, eatLocal, eatNonlocal);
415 cu_atomdata_t *adat = cu_nb->atdat;
416 cu_timers_t *t = cu_nb->timers;
417 bool bDoTime = cu_nb->bDoTime;
418 cudaStream_t stream = cu_nb->stream[iloc];
420 bool bCalcEner = flags & GMX_FORCE_VIRIAL;
421 bool bCalcFshift = flags & GMX_FORCE_VIRIAL;
423 /* don't launch non-local copy-back if there was no non-local work to do */
424 if (iloc == eintNonlocal && cu_nb->plist[iloc]->nsci == 0)
429 /* calculate the atom data index range based on locality */
433 adat_len = adat->natoms_local;
434 adat_end = cu_nb->atdat->natoms_local;
438 adat_begin = adat->natoms_local;
439 adat_len = adat->natoms - adat->natoms_local;
440 adat_end = cu_nb->atdat->natoms;
443 /* beginning of timed D2H section */
446 stat = cudaEventRecord(t->start_nb_d2h[iloc], stream);
447 CU_RET_ERR(stat, "cudaEventRecord failed");
450 if (!cu_nb->bUseStreamSync)
452 /* For safety reasons set a few (5%) forces to NaN. This way even if the
453 polling "hack" fails with some future NVIDIA driver we'll get a crash. */
454 for (int i = adat_begin; i < 3*adat_end + 2; i += adat_len/20)
457 nbatom->out[0].f[i] = NAN;
460 if (numeric_limits<float>::has_quiet_NaN)
462 nbatom->out[0].f[i] = numeric_limits<float>::quiet_NaN();
467 nbatom->out[0].f[i] = GMX_REAL_MAX;
472 /* Set the last four bytes of the force array to a bit pattern
473 which can't be the result of the force calculation:
474 max exponent (127) and zero mantissa. */
475 *(unsigned int*)&nbatom->out[0].f[adat_end*3 - 1] = poll_wait_pattern;
478 /* With DD the local D2H transfer can only start after the non-local
479 kernel has finished. */
480 if (iloc == eintLocal && cu_nb->bUseTwoStreams)
482 stat = cudaStreamWaitEvent(stream, cu_nb->nonlocal_done, 0);
483 CU_RET_ERR(stat, "cudaStreamWaitEvent on nonlocal_done failed");
487 cu_copy_D2H_async(nbatom->out[0].f + adat_begin * 3, adat->f + adat_begin,
488 (adat_len)*sizeof(*adat->f), stream);
490 /* After the non-local D2H is launched the nonlocal_done event can be
491 recorded which signals that the local D2H can proceed. This event is not
492 placed after the non-local kernel because we want the non-local data
494 if (iloc == eintNonlocal)
496 stat = cudaEventRecord(cu_nb->nonlocal_done, stream);
497 CU_RET_ERR(stat, "cudaEventRecord on nonlocal_done failed");
500 /* only transfer energies in the local stream */
506 cu_copy_D2H_async(cu_nb->nbst.fshift, adat->fshift,
507 SHIFTS * sizeof(*cu_nb->nbst.fshift), stream);
513 cu_copy_D2H_async(cu_nb->nbst.e_lj, adat->e_lj,
514 sizeof(*cu_nb->nbst.e_lj), stream);
515 cu_copy_D2H_async(cu_nb->nbst.e_el, adat->e_el,
516 sizeof(*cu_nb->nbst.e_el), stream);
522 stat = cudaEventRecord(t->stop_nb_d2h[iloc], stream);
523 CU_RET_ERR(stat, "cudaEventRecord failed");
527 /* Atomic compare-exchange operation on unsigned values. It is used in
528 * polling wait for the GPU.
530 static inline bool atomic_cas(volatile unsigned int *ptr,
537 return tMPI_Atomic_cas((tMPI_Atomic_t *)ptr, oldval, newval);
539 gmx_incons("Atomic operations not available, atomic_cas() should not have been called!");
544 void nbnxn_cuda_wait_gpu(nbnxn_cuda_ptr_t cu_nb,
545 const nbnxn_atomdata_t *nbatom,
547 real *e_lj, real *e_el, rvec *fshift)
549 /* NOTE: only implemented for single-precision at this time */
551 int i, adat_end, iloc = -1;
552 volatile unsigned int *poll_word;
554 /* determine interaction locality from atom locality */
559 else if (NONLOCAL_A(aloc))
566 sprintf(stmp, "Invalid atom locality passed (%d); valid here is only "
567 "local (%d) or nonlocal (%d)", aloc, eatLocal, eatNonlocal);
571 cu_plist_t *plist = cu_nb->plist[iloc];
572 cu_timers_t *timers = cu_nb->timers;
573 wallclock_gpu_t *timings = cu_nb->timings;
574 nb_staging nbst = cu_nb->nbst;
576 bool bCalcEner = flags & GMX_FORCE_VIRIAL;
577 bool bCalcFshift = flags & GMX_FORCE_VIRIAL;
579 /* turn energy calculation always on/off (for debugging/testing only) */
580 bCalcEner = (bCalcEner || always_ener) && !never_ener;
582 /* Launch wait/update timers & counters, unless doing the non-local phase
583 when there is not actually work to do. This is consistent with
584 nbnxn_cuda_launch_kernel.
586 NOTE: if timing with multiple GPUs (streams) becomes possible, the
587 counters could end up being inconsistent due to not being incremented
588 on some of the nodes! */
589 if (iloc == eintNonlocal && cu_nb->plist[iloc]->nsci == 0)
594 /* calculate the atom data index range based on locality */
597 adat_end = cu_nb->atdat->natoms_local;
601 adat_end = cu_nb->atdat->natoms;
604 if (cu_nb->bUseStreamSync)
606 stat = cudaStreamSynchronize(cu_nb->stream[iloc]);
607 CU_RET_ERR(stat, "cudaStreamSynchronize failed in cu_blockwait_nb");
611 /* Busy-wait until we get the signal pattern set in last byte
612 * of the l/nl float vector. This pattern corresponds to a floating
613 * point number which can't be the result of the force calculation
614 * (maximum, 127 exponent and 0 mantissa).
615 * The polling uses atomic compare-exchange.
617 poll_word = (volatile unsigned int*)&nbatom->out[0].f[adat_end*3 - 1];
618 while (atomic_cas(poll_word, poll_wait_pattern, poll_wait_pattern)) {}
621 /* timing data accumulation */
624 /* only increase counter once (at local F wait) */
628 timings->ktime[plist->bDoPrune ? 1 : 0][bCalcEner ? 1 : 0].c += 1;
632 timings->ktime[plist->bDoPrune ? 1 : 0][bCalcEner ? 1 : 0].t +=
633 cu_event_elapsed(timers->start_nb_k[iloc], timers->stop_nb_k[iloc]);
635 /* X/q H2D and F D2H timings */
636 timings->nb_h2d_t += cu_event_elapsed(timers->start_nb_h2d[iloc],
637 timers->stop_nb_h2d[iloc]);
638 timings->nb_d2h_t += cu_event_elapsed(timers->start_nb_d2h[iloc],
639 timers->stop_nb_d2h[iloc]);
641 /* only count atdat and pair-list H2D at pair-search step */
644 /* atdat transfer timing (add only once, at local F wait) */
648 timings->pl_h2d_t += cu_event_elapsed(timers->start_atdat,
652 timings->pl_h2d_t += cu_event_elapsed(timers->start_pl_h2d[iloc],
653 timers->stop_pl_h2d[iloc]);
657 /* add up energies and shift forces (only once at local F wait) */
668 for (i = 0; i < SHIFTS; i++)
670 fshift[i][0] += nbst.fshift[i].x;
671 fshift[i][1] += nbst.fshift[i].y;
672 fshift[i][2] += nbst.fshift[i].z;
677 /* turn off pruning (doesn't matter if this is pair-search step or not) */
678 plist->bDoPrune = false;
681 /*! Return the reference to the nbfp texture. */
682 const struct texture<float, 1, cudaReadModeElementType>& nbnxn_cuda_get_nbfp_texref()
687 /*! Return the reference to the coulomb_tab. */
688 const struct texture<float, 1, cudaReadModeElementType>& nbnxn_cuda_get_coulomb_tab_texref()
690 return coulomb_tab_texref;
693 /*! Set up the cache configuration for the non-bonded kernels,
695 void nbnxn_cuda_set_cacheconfig(cuda_dev_info_t *devinfo)
699 for (int i = 0; i < eelCuNR; i++)
701 for (int j = 0; j < nEnergyKernelTypes; j++)
703 for (int k = 0; k < nPruneKernelTypes; k++)
705 /* Legacy kernel 16/48 kB Shared/L1
706 * No analytical Ewald!
708 if (i != eelCuEWALD_ANA && i != eelCuEWALD_ANA_TWIN)
710 stat = cudaFuncSetCacheConfig(nb_legacy_kfunc_ptr[i][j][k], cudaFuncCachePreferL1);
711 CU_RET_ERR(stat, "cudaFuncSetCacheConfig failed");
714 if (devinfo->prop.major >= 3)
716 /* Default kernel on sm 3.x 48/16 kB Shared/L1 */
717 stat = cudaFuncSetCacheConfig(nb_default_kfunc_ptr[i][j][k], cudaFuncCachePreferShared);
721 /* On Fermi prefer L1 gives 2% higher performance */
722 /* Default kernel on sm_2.x 16/48 kB Shared/L1 */
723 stat = cudaFuncSetCacheConfig(nb_default_kfunc_ptr[i][j][k], cudaFuncCachePreferL1);
725 CU_RET_ERR(stat, "cudaFuncSetCacheConfig failed");